Sinking Ships

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Lobo316
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Sinking Ships

Post by Lobo316 »

Forgive all the ship related questions I've posted recently here (if you can't tell where my current game is taking place, lol).

Question, if a cargo ship (carvale class) has a hole in the hold (say, in the bottom of the ship) about the size of a ballista bolt, will that ship sink? How much water will come in before bouancy can equal out?

Same questions if he hole is in the size of the cargo hold (I'm talking the lowest hold) as opposed to the bottom.

I'm trying to envision the ship being partially flooded (say three feet of water) in the lowest hold, but not sinking. It's been adrift for as much as a week. Is it possible for the hold to have taken on water, but not sink (mind you, the hole would not have been patched, covered or repaired...the ships crew is abandoned or dead).

Thanks!! I'm running this game tomorrow, so any replies are much appreciated. Worst comes to worst, I'll just not have the hold flooded at all.

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Go0gleplex
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Re: Sinking Ships

Post by Go0gleplex »

The ship will sink if the hole isn't patched. Most wooden sailing ships traveled with stone ballast loaded between the keel of the ship and lowest deck. That weight alone would tend to drag the ship down with compromised hull integrity. However, there is also the weight of the wood used to construct the ship to consider. Wood that is not in contact with the water will not have it's buoyancy added to the equation, instead it will act as yet more weight to drive the ship under. By the time it comes in contact, the volume of water contained in the ship will have become additional weight itself offsetting any buoyancy of the wooden mass under the water surface.

Now, if the deck above the puncture were somehow sealed (impossible with most wooden ships), the ship might have a chance and would be floundering low in the water. But that would be the only chance I could see and only considers that the vessel has been in calm waters, storm waves crashing onto the deck and flooding the lower compartments would be just as deadly (and often was) as the puncture of the hull.
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kreider204
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Re: Sinking Ships

Post by kreider204 »

The 1st ed. AD&D DMG has a bunch of info on ship combat, etc. When I get a sec, I'll take a look and see what I can find about that.

EDIT: Not a ton of detail about it, pretty much just says that a ship with a hole will sink in 1-12 turns, depending on the size of the hole and the ship.

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mgtremaine
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Re: Sinking Ships

Post by mgtremaine »

DMG pg 54-55

Summary.... Assign Haul points based on size and use Siege Weapons to damage it. Damage equal to 1/3 haul value can be repaired at sea, over 1/2 must be put into port. [So it sounds like you do not sink until you are out of haul points]

Type of Vessel >> Hull Value Range
Rowboal >> 1-4
Barge Small, >> 1-6
Barge large >> 2-8
Galley Small >> 2-12
Galley large >> 4-16
Merchant Small >> 6-36
Merchant large >> 12-48
Warship >> 7-42


Siege Attack Value is page 109 but sadly Ballista is missing from the chart... Light Ccatapult vs wood is 4 so 2 is about right.... See if that helps
-Mike

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Dracyian
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Re: Sinking Ships

Post by Dracyian »

Another problem is wood is porous and gets heavier as it gets wets which increases density and makes lower and more wood gets wet and so on so forth,

However one thing I can see since we are in a world of Magic and Fantasy is that wood became enchanted and sealed off the lower hold with water on it and became alive drinking the water for live giving nutrients and stuff as it came in due to a slow leak, like maybe the ship was hit with a ballista bolt and a druid cast warp wood and it sealed most of the hole leaving a smidgen of wood left and the god or goddess the druid served saw the druids loyal service and didn't want his efforts to be in vain and to make the ship a more natural place for a druid brought the wood back to life, and that would also explain how this ship can float adrift for as long as you want it to. Just thinking outloud

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Re: Sinking Ships

Post by NJPDX »

I don't really want to nit pick too much, but a wooden ship hull would not be as porous and prone to absorption as you might think. They would almost certainly sealed with a heavy layer of pitch or tar.

If you put a hole below the water line, it's just a matter of the weight of the water rushing in and overcoming a boat's displacement before it would be scuttled or at least swamped.

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Re: Sinking Ships

Post by Dracyian »

NJPDX wrote:I don't really want to nit pick too much, but a wooden ship hull would not be as porous and prone to absorption as you might think. They would almost certainly sealed with a heavy layer of pitch or tar.

If you put a hole below the water line, it's just a matter of the weight of the water rushing in and overcoming a boat's displacement before it would be scuttled or at least swamped.
Its not the hull, its all the wood on the inside, even though it is sealed with pitch and tar with the water sitting on it there will still be absorption, may not be nearly as fast or as much as my previous post leads people to believe due to my lack of effort put into my words, especially if you have a multi hold boat

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Re: Sinking Ships

Post by Arduin »

Lobo316 wrote:Question, if a cargo ship (carvale class) has a hole in the hold (say, in the bottom of the ship) about the size of a ballista bolt, will that ship sink? How much water will come in before bouancy can equal out?
1) it would take LONG time.
2) would happen only if no one quickly patched (extremely easy to do) or no spare sailor to bail.
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NJPDX
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Re: Sinking Ships

Post by NJPDX »

Dracyian wrote:
NJPDX wrote:I don't really want to nit pick too much, but a wooden ship hull would not be as porous and prone to absorption as you might think. They would almost certainly sealed with a heavy layer of pitch or tar.

If you put a hole below the water line, it's just a matter of the weight of the water rushing in and overcoming a boat's displacement before it would be scuttled or at least swamped.
Its not the hull, its all the wood on the inside, even though it is sealed with pitch and tar with the water sitting on it there will still be absorption, may not be nearly as fast or as much as my previous post leads people to believe due to my lack of effort put into my words, especially if you have a multi hold boat
The inrush of water is about 99.9% more important to a vessels buoyancy than it becoming water logged ... even in those areas not coated in tar or pitch and I only assumed a hole in the hull because that's the only way the "other" wood could become immersed.

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Re: Sinking Ships

Post by Dracyian »

true

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Lobo316
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Re: Sinking Ships

Post by Lobo316 »

Cool, thanks for all the repliesl gang. I ended up running the encounter with the hold dry. Just didn't feel like addressing the "physics" of it, but I will keep all this in mind should this come up again. The party are currently sticking the coastline, but traveling by sea, so we'll see if i throw another such encounter thier way.

Thanks Again!!!!

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Re: Sinking Ships

Post by Go0gleplex »

Well darn. I was going to calculate the pressure head and flow rate through the hole too. Even got my fluid mechanics book out. lol Guess-timate before settling was about 5-10 gallons per second through an 8" dia hole with a 50% blockage. That would increase as the ship sank due to an increase in head pressure as long as the water elevation in the ship was less than the depth of the hole from the surface. Then it would start slowing and evening out. But hey...who needs us silly engineering types to have fun, eh? LOL (no, I'm not taking this that seriously...)
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Re: Sinking Ships

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Go0gleplex wrote: Guess-timate before settling was about 5-10 gallons per second through an 8" dia hole with a 50% blockage. That would increase as the ship sank due to an increase in head pressure as long as the water elevation in the ship was less than the depth of the hole from the surface. Then it would start slowing and evening out. But hey...who needs us silly engineering types to have fun, eh? LOL (no, I'm not taking this that seriously...)
A ballista bolt is only ~1" in diameter...
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Re: Sinking Ships

Post by Go0gleplex »

Arduin wrote:
Go0gleplex wrote: Guess-timate before settling was about 5-10 gallons per second through an 8" dia hole with a 50% blockage. That would increase as the ship sank due to an increase in head pressure as long as the water elevation in the ship was less than the depth of the hole from the surface. Then it would start slowing and evening out. But hey...who needs us silly engineering types to have fun, eh? LOL (no, I'm not taking this that seriously...)
A ballista bolt is only ~1" in diameter...
Izzat so. I was thinking a bit larger, plus wood buckling to some degree. Still, even with that small of a hole you're looking at 1-2 gallons or so per second. 50 feet of head pressure will send water 30' into the air through a 2" hole from a water main...and that's just gravity working. :) So with a shot below the water line, assuming about 10 feet of head pressure, it makes for a fun water feature. lol
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Arduin
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Re: Sinking Ships

Post by Arduin »

Go0gleplex wrote:Izzat so. I was thinking a bit larger, plus wood buckling to some degree. Still, even with that small of a hole you're looking at 1-2 gallons or so per second. 50 feet of head pressure
If from a ballista bolt it is likely to maybe be 1'-3' under water. So, maybe not that much pressure? Also the wood is too thick to buckle from something like that.
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Re: Sinking Ships

Post by Dracyian »

Arduin wrote:
Go0gleplex wrote:Izzat so. I was thinking a bit larger, plus wood buckling to some degree. Still, even with that small of a hole you're looking at 1-2 gallons or so per second. 50 feet of head pressure
If from a ballista bolt it is likely to maybe be 1'-3' under water. So, maybe not that much pressure? Also the wood is too thick to buckle from something like that.
Unless Magically propelled

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Re: Sinking Ships

Post by Arduin »

Dracyian wrote:
Arduin wrote:
Go0gleplex wrote:Izzat so. I was thinking a bit larger, plus wood buckling to some degree. Still, even with that small of a hole you're looking at 1-2 gallons or so per second. 50 feet of head pressure
If from a ballista bolt it is likely to maybe be 1'-3' under water. So, maybe not that much pressure? Also the wood is too thick to buckle from something like that.
Unless Magically propelled
Truth. But still a non-issue for a crewed vessel.
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Re: Sinking Ships

Post by Just Jeff »

In an AD&D game I once used a passwall spell to put a big hole in a ship's hull. Cleverly, the DM had me sucked into a ship. A high level cleric on the ship then used a lower water followed by a warp wood (I think) to fix the problem, leaving me trapped. Had to dimension door out of there to avoid getting in a knock-down drag-out fight in the lowest hold of a ship full of unfriendlies.

I loved that naval battle. :D

ETA: Ah, now I remember. It was dispel magic followed by lower water.

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